CS8920 datasheet(53/66 Pages) CIRRUS

53 / 66 page

AN84REV1

CS8920 Technical Reference Manual

3.5 Programming and Initializing

the EEPROM

The contents of the EEPROM may

either be pre-programmed in an stand-

alone EEPROM programmer or

programmed after installation through

the CS8920’s serial interface.

When programming an EEPROM for

the first time via the CS8920's serial

interface after the EEPROM has been

installed on the adapter, the CS8920's

auxiliary key must be used.

On reset, if the Reset Configuration

Block's checksum is invalid ( typically

the case with a new EEPROM

installation), the CS8920 performs an

EEPROM reset. This reset reloads all of

the CS8920's PacketPage registers with

their default values, thereby leaving the

CS8920 inactive. In this state, all

communication with the CS8920 using

normal IO is disabled. Further, the

CS8920 will no longer respond to the

standard PnP initiation key.

However, writing the CS8920-specific

auxiliary initiation key to the PnP write-

data port after an EEPROM reset will

enable the CS8920 to respond to

standard PnP commands. The adapter is

then configured with an IO base and

made active by writing the appropriate

commands and data to the PnP write-

data port. Once the CS8920 has been

made active and the IO base address is

assigned via the PnP interface, the

EEPROM may be programmed in the

usual manner. Refer to the CS8920 Data

Sheet for more information on

programming the EEPROM via the

CS8920’s serial interface.

WARNING: The CS8920 will respond

to the auxiliary key only after an

EEPROM reset has occurred. In

addition, the CS8920 will not respond to

the auxiliary initiation key if the PnP

functions of the CS8920 are disabled.

Therefore, it is important to ensure that

the CS8920 is explicitly activated from

the Reset Configuration Block whenever

a valid Reset Configuration Block is

present and the CS8920's PnP functions

are disabled. Failure to do so will make

it impossible to communicate with the

CS8920 and to re-program the

EEPROM without first removing it from

the adapter and installing in another

adapter or stand-alone EEPROM

programming device.

3.5.1 Maintaining EEPROM

Configuration Data

Crystal provides two utilities for

maintaining the configuration

information stored in the EEPROM.

One is designed to be used by OEMs to

initialize the EEPROM’s contents before

shipping to the end-user (OEM

EEPROM Programming Utility).

The other is a DOS-based Setup and

Installation utility run by the end-user at

the time the adapter is installed. The

Setup and Installation utility allows the

end-user to configure the adapter for a

specific system. Refer to Section 4.2 for

more information on the DOS Setup and

Installation utility.

The OEM is left to determine the best

procedure for programming EEPROMs

CS8920 Datasheet(PDF) 53 Page - Cirrus Logic

CS8920 Datasheet(HTML) 53 Page - Cirrus Logic

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